Bottom Line:
Low Birth Weight (LBW) is a surrogate for fetal undernutrition and is associated with impaired nephron development in utero.As compared to patients without LBW, patients with LBW had a hazard ratio (HR) of 2.0 (95% confidence interval 1.1-3.7) for the total cohort, 2.2 (1.1-4.4) for males and 1.3 (0.30-5.8) for females.Further analyses showed that as compared to patients with neither LBW nor SGA, patients with either SGA or LBW did not have significantly increased risks (HRs of 1.3-1.4) but patients who were both LBW and SGA had an increased risk (HR 3.2 (1.5-6.8).

Background: Low Birth Weight (LBW) is a surrogate for fetal undernutrition and is associated with impaired nephron development in utero. In this study, we investigate whether having been born LBW and/or small for gestational age (SGA) predict progression to ESRD in IgA nephropathy (IgAN) patients.

Study design: Retrospective registry-based cohort study.

Settings & participants: The Medical Birth Registry has recorded all births since 1967 and the Norwegian Renal Registry has recorded all patients with ESRD since 1980. Based on data from the Norwegian Kidney Biopsy Registry we included all patients diagnosed with IgAN in Norway from 1988-2013. These registries were linked and we analysed risk of progression to ESRD associated with LBW (defined as birth weight less than the 10th percentile) and/or SGA (defined as birth weight less than the 10th percentile for gestational week) by Cox regression statistics.

Results: We included 471 patients, of whom 74 developed ESRD. As compared to patients without LBW, patients with LBW had a hazard ratio (HR) of 2.0 (95% confidence interval 1.1-3.7) for the total cohort, 2.2 (1.1-4.4) for males and 1.3 (0.30-5.8) for females. Corresponding HRs for SGA were 2.2 (1.1-4.2), 2.7 (1.4-5.5) and 0.8 (0.10-5.9). Further analyses showed that as compared to patients with neither LBW nor SGA, patients with either SGA or LBW did not have significantly increased risks (HRs of 1.3-1.4) but patients who were both LBW and SGA had an increased risk (HR 3.2 (1.5-6.8).

Limitation: Mean duration of follow-up only 10 years and maximum age only 46 years.

Conclusion: Among IgAN patients, LBW and/or SGA was associated with increased risk for progression to ESRD, the association was stronger in males.

pone.0153819.g001: Cumulative Probability of ESRD in patients with IgAN according to whether or not the patient had LBW.

Mentions:
When the analyses were done separately for male and female patients, both SGA and LBW remained statistically significant predictors of ESRD in males, but there was no excess risk in females (Table 2 and Figs 1 and 2). After adjustments for eGFR, neither LBW nor SGA were significantly associated with risk of ESRD. A similar analysis for preterm birth, showed a non-significant higher risk of ESRD for the total cohort and for both gender subgroups.

pone.0153819.g001: Cumulative Probability of ESRD in patients with IgAN according to whether or not the patient had LBW.

Mentions:
When the analyses were done separately for male and female patients, both SGA and LBW remained statistically significant predictors of ESRD in males, but there was no excess risk in females (Table 2 and Figs 1 and 2). After adjustments for eGFR, neither LBW nor SGA were significantly associated with risk of ESRD. A similar analysis for preterm birth, showed a non-significant higher risk of ESRD for the total cohort and for both gender subgroups.

Bottom Line:
Low Birth Weight (LBW) is a surrogate for fetal undernutrition and is associated with impaired nephron development in utero.As compared to patients without LBW, patients with LBW had a hazard ratio (HR) of 2.0 (95% confidence interval 1.1-3.7) for the total cohort, 2.2 (1.1-4.4) for males and 1.3 (0.30-5.8) for females.Further analyses showed that as compared to patients with neither LBW nor SGA, patients with either SGA or LBW did not have significantly increased risks (HRs of 1.3-1.4) but patients who were both LBW and SGA had an increased risk (HR 3.2 (1.5-6.8).

Background: Low Birth Weight (LBW) is a surrogate for fetal undernutrition and is associated with impaired nephron development in utero. In this study, we investigate whether having been born LBW and/or small for gestational age (SGA) predict progression to ESRD in IgA nephropathy (IgAN) patients.

Study design: Retrospective registry-based cohort study.

Settings & participants: The Medical Birth Registry has recorded all births since 1967 and the Norwegian Renal Registry has recorded all patients with ESRD since 1980. Based on data from the Norwegian Kidney Biopsy Registry we included all patients diagnosed with IgAN in Norway from 1988-2013. These registries were linked and we analysed risk of progression to ESRD associated with LBW (defined as birth weight less than the 10th percentile) and/or SGA (defined as birth weight less than the 10th percentile for gestational week) by Cox regression statistics.

Results: We included 471 patients, of whom 74 developed ESRD. As compared to patients without LBW, patients with LBW had a hazard ratio (HR) of 2.0 (95% confidence interval 1.1-3.7) for the total cohort, 2.2 (1.1-4.4) for males and 1.3 (0.30-5.8) for females. Corresponding HRs for SGA were 2.2 (1.1-4.2), 2.7 (1.4-5.5) and 0.8 (0.10-5.9). Further analyses showed that as compared to patients with neither LBW nor SGA, patients with either SGA or LBW did not have significantly increased risks (HRs of 1.3-1.4) but patients who were both LBW and SGA had an increased risk (HR 3.2 (1.5-6.8).

Limitation: Mean duration of follow-up only 10 years and maximum age only 46 years.

Conclusion: Among IgAN patients, LBW and/or SGA was associated with increased risk for progression to ESRD, the association was stronger in males.